Submitted by Daniella Santos (daniella.santos@ufma.br) on 2017-12-06T15:15:55Z No. of bitstreams: 1 ClemesonVale.pdf: 2633941 bytes, checksum: d3b7926b71b1f8326929442dd906fefa (MD5) / Made available in DSpace on 2017-12-06T15:15:55Z (GMT). No. of bitstreams: 1 ClemesonVale.pdf: 2633941 bytes, checksum: d3b7926b71b1f8326929442dd906fefa (MD5) Previous issue date: 2014-04-30 / CAPES / The constant concerns over the unsustainable use of natural resources, coupled with rapid population growth, direct them to the productive process of maximizing resources systems to provide greater increases in production to minimize impacts to the environment yields. The objective of this research was to evaluate the performance of maize in no-tillage in legume straw depending on the spatial variability of soil chemical properties and nutrient input in a Dystrophic cohesive oxisol. The experiment was conducted in a 0.6 ha area containing two environments (without legumes and pulses) and 170 sampling points regularly dispersed (7.0 x 5.0 m) for chemical soil variability and productive maize yields. Data were initially analyzed using descriptive statistics and later by geostatistical methods. The interaction between soil chemical properties and yield of corn production was assessed by Pearson correlation to 5%. There was an increase in levels of soil chemical properties in the area with legumes compared to the area without legumes, proving the applicability of this management system to improve the chemical quality of the soil due to continuous addition of plant residues. Found the presence of spatial variability for all soil chemical properties and productive yield with spatial dependence ranged from moderate to strong, allowing reveal through thematic maps the potentialities and limitations of the production system. The productive efficiency, productivity specifically, correlated positively with calcium, sum of bases, phosphorus, potassium, base saturation and cation exchange capacity. / As constantes preocupações com o uso insustentável dos recursos naturais, juntamente com o acelerado crescimento demográfico, direcionam os sistemas produtivos ao processo de maximização dos recursos a fim de proporcionar maiores incrementos nos rendimentos produtivos com minimização dos impactos ao ambiente. O objetivo da presente pesquisa foi avaliar o desempenho produtivo do milho em sistema de plantio direto na palha de leguminosas em função da variabilidade espacial dos atributos químicos do solo e do aporte de nutrientes num Latossolo Amarelo distrocoeso. O experimento foi conduzido numa área de 0,6 ha contendo dois ambientes (sem leguminosas e com leguminosas) e 170 pontos amostrais regularmente dispersos (7,0 x 5,0 m) para determinação da variabilidade química do solo e dos rendimentos produtivos do milho. Os dados foram inicialmente analisados por meio da estatística escritiva e posteriormente por métodos geoestatísticos. A interação entre os atributos químicos do solo e o rendimento produtivo do milho foi verificada pela correlação de Pearson a 5%. Verificou-se a elevação nos teores dos atributos químicos do solo na área com leguminosas quando comparado com a área sem leguminosas, comprovando a aplicabilidade desse sistema de manejo para a melhoria da qualidade química do solo em consequência da adição continuada de resíduos vegetais. Constatou-se a presença de variabilidade espacial para todos os atributos químicos do solo e rendimento produtivo, com grau de dependência espacial que variaram de moderado a forte, o que possibilitou revelar por meio de mapas temáticos as potencialidades e limitações do sistema de produção. O rendimento produtivo, especificamente a produtividade, apresentou correlação positiva com o cálcio, a soma de bases, o fósforo, o potássio, a saturação por bases e a capacidade de troca catiônica.

Made available in DSpace on 2017-07-10T17:37:01Z (GMT). No. of bitstreams: 1 Alfredo_Jose_Alves_Neto.pdf: 2227704 bytes, checksum: 41f3972bccb1f6dc8e4ce7ded03e7737 (MD5) Previous issue date: 2015-08-12 / Nutrients contained in swine wastewater (SW), are unbalanced and not fully available for the first crop, with the need for regionalized research, taking into account the characteristics of each site, such as rainfall, soil type and cropping systems of each region. With the objective of evaluating the influence of applications of ARS doses in soybean crop and second crop corn, chemical and physical properties of the soil, an experiment was conducted from september 2013 to august 2014, in the municipality of Cafelândia, western of Paraná, in the Copacol Center of Agricultural Research - CPA Copacol, in Dystroferric Red Latosol. In this experiment, was used five swine wastewater doses (0, 35, 70, 105 and 140 m3 ha-1 yr-1) and two sources of mineral fertilizer, absence and presence. The statistical design, was a randomized block with split plots, with four repetitions, allocated in the main plots factor doses, and in the subplots was allocated the mineral fertilizer factor, the soybean crop (summer 13/14) and maize second crop (winter 14/14). Biometric variables were evaluated, leaf levels of N, P, K, Cu and Zn in soybean and corn with their respective yields, with subsequent determination of economic analysis of SW doses. After second crop corn harvest, soil samples were collected in the layers 0 - 0,10 and 0,10 - 0,20 m to determine the C organic, P, K, Cu and Zn. Undisturbed soil core samples were collected in the layers 0 - 0,10, 0,10 - 0,20 and 0,20 - 0,30 m to determination of soil physical properties. With increasing of SW doses, a reduction in the biological nitrogen fixation in soybean, in contrast with increases in the weight of a thousand grains. In second crop corn, the SW doses increased productivity, thousand grain weight and grains moisture content. Identified an increase in the levels of P, K, Cu and Zn in the layer of 0 - 0,10 m, and increase in the P content in the layer of 0,10 - 0,20 m. The applications of SW doses kept the physical soil quality in layers sampled / Os nutrientes contidos na água residuária de suinocultura (ARS), são desbalanceados e não totalmente disponíveis no primeiro cultivo, havendo a necessidade de pesquisas regionalizadas levando em conta particularidades de cada local, como o regime pluviométrico, tipo de solo e os sistemas de cultivos. Com o objetivo de avaliar a influência das aplicações de doses de ARS nas culturas de soja e milho segunda safra, nos atributos químicos e físicos do solo, um experimento foi conduzido nos meses de setembro de 2013 a agosto de 2014, no município de Cafelândia, região oeste do Paraná, no centro de pesquisa agrícola Copacol CPA Copacol, em Latossolo Vermelho Distroférrico típico. Foram utilizadas cinco doses de água resíduária de suinocultura, (0, 35, 70, 105 e 140 m3 ha-1 ano-1), e duas fontes de adubação mineral, ausência e presença. O delineamento utilizado foi de blocos casualizados com parcelas subdivididas, com quatro repetições, sendo alocado nas parcelas principais o fator doses, e nas subparcelas alocado o fator adubação mineral, com os cultivos de soja (verão 13/14) e milho segunda safra (inverno 14/14). Foram avaliadas as variáveis biométricas, os teores foliares de N, P, K, Cu e Zn das culturas de soja e milho e as suas respectivas produtividades, com posterior determinação de análise econômica das doses de ARS. Após a colheita do milho segunda safra, foram coletadas amostras de solo nas profundidades de 0 - 0,10 e 0,10-0,20 m para determinação dos teores de C orgânico, P, K, Cu e Zn. Amostras indeformadas com anéis volumétricos foram retiradas nas profundidades de 0 - 0,10, 0,10 - 0,20 e 0,20 - 0,30 m, para determinação dos atributos físicos do solo. Com o aumento das doses de ARS, houve redução na fixação biológica de nitrogênio na cultura da soja, em contrapartida, com aumento na massa de mil grãos. Na cultura do milho, as doses de ARS aumentaram a produtividade, a massa de mil grãos e o teor de umidade dos grãos. Evidenciou-se aumento nos teores de P, K, Cu e Zn, na profundidade de 0 - 0,10 m, e aumento no teor de P na profundidade de 0,10 - 0,20 m. As aplicações das doses de ARS conservaram a qualidade física do solo

A agropecuária tem um importante papel na economia do Brasil. Fertilizantes nitrogenados estão entre os principais insumos da agropecuária mundial, e o seu uso em grandes volumes geram problemas ambientais. Sistemas Integrados de Produção Agropecuária (SIPAs) buscam a maior eficiência no uso dos recursos naturais em comparação às monoculturas agrícolas, reduzir as perdas de nutrientes e promover a ciclagem do nitrogênio (N). O animal é considerado um catalizador da ciclagem de nutrientes e em um SIPA a intensidade de pastejo e a fertilização, são as principais variáveis a ser manejada na fase pastagem, pois determinam a cobertura do solo, que é transferida para a fase lavoura e influencia a sua produtividade. A soja e o milho estão entre as mais importantes culturas da agricultura Brasileira. A soja tem o potencial de suprir parte das suas demandas através da Fixação Biológica de N, já o milho é dependente do solo para atender a sua necessidade por N. A adubação antecipada baseia-se em que a exportação de nutrientes na fase lavoura é maior do que na fase pastagem. Propõe-se que a adubação seja realizada no inverno, promovendo maiores rendimentos da fase pastagem e a ciclagem dos nutrientes para a fase lavoura. O objetivo deste trabalho foi avaliar o efeito da adubação nitrogenada em pastagem de azevém pastejada por ovinos sob diferentes intensidades de pastejo e métodos de pastoreio no índice de nutrição nitrogenada das culturas de verão em SIPAs. Este estudo foi realizado entre os anos 2013 e 2014, em um experimento de longa duração iniciado em 2003, em SIPA, o qual é composto por 32 unidades experimentais delineados em blocos casualizados, com quatro tratamentos, dois métodos de pastoreio, contínuo e rotativo, duas intensidades de pastejo, moderada e baixa em pastagem de azevém-anual pastejada por ovinos, no período de inverno e dois sistemas de cultivos de verão, monocultivo de soja e rotação soja/milho, com quatro repetições. A fertilização foi realizada exclusivamente na fase pastagem com 75 kg de N e 60 kg de P2O5 e K2O ha-1. A massa de forragem residual (MFR) foi avaliada ao final da fase pastagem. Durante o verão foram avaliados o rendimento de fitomassa das culturas de verão durante a fase vegetativa, o teor de N na fitomassa e o Índice de Nutrição Nitrogenada (INN) das culturas. Para a cultura do milho, houve efeito das intensidades de pastejo (P<0,05) para INN e MFR. Para as culturas da soja houve efeito das intensidades de pastejo (P<0,05) apenas para a MFR. Não foi encontrada diferença entre os métodos de pastoreio para as duas culturas. A MFR é uma importante fonte de N para a cultura de verão subsequente. Menores intensidades de pastejo resultam em maiores MFR e, consequentemente, maiores INN para a cultura do milho. A adubação nitrogenada antecipada não apresentou efeito sobre a soja uma vez que esta cultura tem a capacidade de atender a sua demanda por N através da Fixação Biológica de N. / Agriculture has an important role in Brazilian economy. Nitrogen fertilizers are among the main inputs of worldwide agriculture, and its use in large volumes has generated environment problems. Integrated Crop Livestock Systems (ICLS) search for a more efficient use of natural resources than monoculture agriculture systems, reduce Nitrogen (N) losses and promote its cycling. The animal is consider a catalyst for nutrient cycling and in an ICLS, the grazing intensity along with fertilization, are the main variable to be manage in the pasture phase, since it determines the soil cover, which is transfer to the crop stage and directly influences its yield. Soybean and maize are among the most important crops of the Brazilian agriculture. Soybean has the potential to attend most of their demands for nitrogen (N) through the Biological Fixation, on the other hand, maize is dependent on soil fertility to attend their need for this nutrient. Early fertilization is based on that the export of nutrients in the crops phases is greater than pasture phase. Is propose that the fertilization should be manage on winter, because it would provide higher yields of pasture phase and recycling of nutrients to the crop stage. The objective of this study was to evaluate the effect of early nitrogen fertilization on Italian ryegrass pasture grazed by sheep under different grazing intensities and grazing methods on ICLS summer crops nitrogen nutrition index. This work was perform between 2013 and 2014, in a long-term ICLS experiment, with 32 experimental units designed in a randomized block with four treatments and four replications. The treatments were two stocking methods, continuous and rotational grazing, two grazing intensities, moderate and low, with Italian ryegrass grazed by sheep on winter, and two cropping systems, soybean monoculture and soybean/maize crop rotation, on summer. The fertilization management was 75 kg of N, 60 kg of P2O5 and K2O ha-1. The residual forage mass (RFM) on the end of grazing phase. During summer were evaluate the crops biomass yield on vegetative phase, the N content on the phytomass, and the crops NNI. On maize crop area were found effect of the grazing intensities (P<0.05) on the RFM and NNI. On soybean crop area was found effect of the grazing intensities (P<0.05) on the RFM. There were no differences between the grazing methods in both crop systems, and on RFM and NNI of soybeans areas (P>0.05). The RFM is an important summer crop N source. Lowest grazing intensities result on higher RFM, and consequently in higher NNI on maize crop. The early fertilization does not cause effects on soybean, once this crop has the ability to meet its demand for N by N Biological Fixation.

Labeled by the National Academy of Engineering (NAE) as one of fourteen Grand Challenges for Engineering, the management of the nitrogen cycle has become an increasingly difficult obstacle for sustainable development. In an effort to help overcome this challenge, the goal of our study is to expand on the limited scientific understanding of how the nitrogen cycle within aquatic environments may be affected by increasing human- and climate-induced changes. To this end, we are using freshwater mussels as a sentinel species to better understand the impacts of ecosystem perturbation on nitrogen processing in large river systems. This was completed by examining the physical, biological, and chemical characteristics of a mussel habitat in the Mississippi River, evaluating the impact of the 2008 floods on the habitat and the ecosystem's nutrient processing, establishing a well-equipped mussel laboratory habitat to investigate mussel behavioral responses, and analyzing highly time resolved data to examine the mussels' contribution to daily nitrate fluxes.

This study was conducted at the Ailao Mountain National Natural Reserve (NNR) in natural vegetation described as: Lithocarpus xylocarpus/Castanopsis wattii (Oak /Chestnut association) forest. Study sites were located in the Xujiaba area of the reserve at an altitude of ~ 2450 m with slopes of 10-15 degrees. This type of forest is believed to be unique to the NEAR area. The forest is floristically characterized by multiple families and genera. It has two tall tree layers, a well-developed bamboo (Sinarundinaria nitida) layer and evergreen fern species. Bryophyte, ferns and lichen occur and abundant epiphytic bryophyte is present on tree boles.A number of important aspects of nutrient cycling, including patterns of biomass and nutrient accumulation; nutrient return in litterfall and release from decomposing leaf litter; annual nutrient uptake and retention, and nutrient input and output budgets through hydrological flux in natural Lithocarpus/Castanopsis forest in the reserve, were investigated.This natural forest is characterized by high biomass accumulation of living and dead materials. Trees account for >90 % of total biomass. Dead wood comprises a high proportion (9-41 %) of total stand biomass. The sequence of inorganic nutrient element content decreased in the order leave s>b ranche s>roots> stems. Elemental content of the total stand decreased in the order of C>Ca>N>K>AI>Mg>P>Fe>Mn. The elements C, Ca and N were mainly in stems while AI and Fe were mainly in roots.Litterfall was sampled using traps during the period 1991-1999. High variations in litter production between years were associated with masting years of canopy species, and exceptional physical events (strong winds and snow). The mean annual litterfall is 7.12 t ha-1 with a bimodal seasonal pattern in litterfall: the main litterfall peak occurred in April-May and a lesser one in October-November. Woody ++ / litter and reproductive parts contribute relatively high proportions in this natural forest compared with other montane forests. Woody litter had low N and P concentrations compared with the leaf and reproductive parts. Elements return to the soil through small litterfall decreases in the order C>N>Ca>K>Mg>Mn>AI>P>Fe.The standard litter-bag technique was used to determine decomposition of leaf litter from three dominant canopy species (L. xylocarpus, L. chintungensis, C. wattii), one dominant understory species (the bamboo S. nitida) and a mixture of dominant bryophytes between Nov. 1997 and Oct. 1999. In each case, fast initial litter decomposition was followed by lower rates. Decomposition rates of canopy species and bamboo leaf litter appear to be controlled by initial concentration of lignin, N and P more than by morphological features of the leaves. P seemed to limit decomposition of all leaf litter, both initially and later. Nutrient release from decomposing leaf litter is in the order of K>Mg>Ca>N>P>~Fe, except for bamboo (S. nitida) K>Ca> P>N>Mg>Mn>Fe.Nutrient fluxes in bulk precipitation, throughfall and stemflow were measured in the natural forest between Jan. 1998 and Dec. 1999. This forest exhibited low interception by the canopy (13 % of total rainfall). N, P, Ca and S annual throughfall inputs were mainly from precipitation, while most of the K and two thirds of the Mg throughfall input was due to canopy leaching. There were significant effects of epiphytes on the amount and chemical composition of stemflow. Water volume and annual amounts of N, Ca and Mg were reduced, while K, P and S 1 were increased in stemflow after removing epiphytes on boles and branches.Plot- and catchment level approaches were applied to determine nutrient output from the ecosystem during the study period. The results indicated that this catchment has a subsurface flow system. ++ / The amounts of percolation water varied with soil depths. Concentrations of all nutrient elements studied were greater in surface water than in soil solution and stream water. The budgets for all nutrient elements between atmospheric inputs and outputs by both seepage and stream flow were positive, except for calcium (negative).This forest appears to be characterized by relatively high nutrient return (5.6-8.0 % of the total storage) and low nutrient retention (2.0-2.7 % of the total storage). The relative rate of nutrient cycling occupies an intermediate position between temperate evergreen broad-leaved forest and tropical montane rain forest, it is closer to montane rain forests in rates of nutrient circulation.

Morella cerifera (L.) Small, the Wax Myrtle, forms both arbuscular mycorrhizas and cluster roots which generally are regarded as alternative adaptations for phosphorus acquisition. But whether or not arbuscular mycorrhizal fungi (AMF) provide any benefit to M. cerifera is not known. Nevertheless, AMF can proliferate extensively within the litter leaves that accumulate beneath M. cerifera. The main objective of this study was to determine if AMF are beneficial to M. cerifera host plants in the presence of leaf litter. In the field, I examined leaf traits that affect the colonization of leaf litter by AMF. I compared AMF colonization of labile versus recalcitrant leaves, and that of leaf pieces with obstructed versus non-obstructed veins. In pot experiments, I examined if labile or recalcitrant litter influences the potential benefit of AMF to M. cerifera, and if nitrogen (N) or phosphorus (P) fertilization influences that benefit in the presence of recalcitrant leaf litter. I found that AMF extensively colonize both labile and recalcitrant leaves, but that they colonize labile leaves more rapidly than recalcitrant leaves. I found significantly less colonization in leaf pieces with obstructed veins than in those with non-obstructed veins which suggests that penetration by the fungi primarily is mechanical and not enzymatic. The pot experiments showed that AMF are parasitic on M. cerifera except when recalcitrant leaf litter is present, and that the effects of AMF on M. cerifera are indirect and mediated through effects of AMF on N-fixing nodule dry weight. In both pot experiments, AMF enhanced litter decomposition and may have enhanced plant P-nutrition. AMF benefited M. cerifera growth in the absence of N fertilization but negatively affected M. cerifera growth when N was added. In the presence of litter, inoculation with AMF increased cluster root formation, suggesting that these two adaptations may be complementary in extremely nutrient-poor soils. Overall, this study shows that M. cerifera does benefit from association with AMF, and it suggests that AMF play a more important role in the acquisition of mineral nutrients from leaf litter than previously recognized.

Three general questions are studied regarding plant carbon allocation strategies. (1) The R* Rule states that the superior competitor in a plant community should exclude all others by minimizing available limiting nutrient concentration below the level needed for survival of its competitors. I asked whether a plant carbon allocation strategy that minimizes the concentration of available limiting nutrient is consistent with Lotka's (1922) conjecture that ecosystems should evolve to maximize total energy flow (primary production). (2) In landscapes such as the Everglades, areas of landscape with higher energy flow (primary production) than the surrounding area also have higher available concentrations of limiting nutrient, rather than lower concentrations, which might be expected from the R* rule. I asked whether this pattern can be explained. (3) I asked how optimal allocation of carbon to plant defense allocation strategies might depend on different conditions of nutrient availability, shading, and herbivory. To address all three questions, I used a model revised from the G'DAY model (Comins and McMurtrie 1993) to study tree allocation of carbon resources between foliage, roots, and defense. With regard to the first question, I found that the allocation strategy that leads to minimum concentration of available nutrients is the same as the strategy for which energy flux to roots, rather than total energy flux, is maximized. Further, I found that the strategy that was competitively dominant was neither the strategy for which total energy flux was maximized, nor that for which available nutrient concentration was minimized. With regard to the second question, I found that, if a patch of vegetation on a landscape is able to capture nutrients from the surrounding landscape, for example, through relatively higher evapotranspiration, it could lead to the opposite of what is expected from the R* rule; that is, available limiting nutrient concentration is maximized when carbon flow to the roots is maximized. With regard to the last question, I found that under high herbivory, the optimal plant strategy for allocation of carbon to defense depends on the available nutrient concentration and amount of radiation to the plant, in agreement with some theoretical predictions.

This thesis characterizes the cycling of carbon, nitrogen and silicon by marine polar diatoms through the aid of a field study and a laboratory study. Field studies were conducted along a transect from Victoria, Canada to Barrow, Alaska and particulate carbon, nitrogen and silicon, chlorophyll a, nitrate, phosphate, silicic acid, and carbon and nitrogen incorporation, along with biogenic silica net incorporation were measured. Total primary production was lowest in the NE Pacific (0.3 to 1.0 mmol m-3 day-1), with new production contributing 17 to 38% of total production. Biogenic silica net incorporation in the upper 250 m of the water column in the NE Pacific was relatively low (0 to 0.12 mmol m-3 day-1), but positive, indicating the opportunity for export from the euphotic zone. Total primary, new production and production by siliceous plankton was highest in the Chukchi Sea, due to the influence of nutrient influx from the Anadyr Stream. Total primary production ranged from 1.0 to 3.2 mmol m-3 day-1, new production contributed as much as 56% of total production, and the production by siliceous phytoplankton was as high as 5.6 mmol m-3 day-1. Siliceous biomass was usually recycled in the upper water column of the Bering and the Chukchi Seas, in contrast to the NE Pacific. The interference of lithogenic material on the measurement of biogenic silica was explored using data from the Bering and Chukchi Seas. Results show that lithogenic interference is location specific. Sediment clay composition data should be considered when high concentrations of lithogenic silica are present. The laboratory study examined the effects of different irradiance and temperature conditions on two polar diatom species: Thalassiosira antarctica and Porosira glacialis. Temperature and irradiance had species-specific effects on the cellular content of carbon, nitrogen and silicon. The relationship between growth rate and silicon content for T. antarctica showed that silicon content increased as growth rate decreased, which is in agreement with previous studies. However, this relationship did not hold for P. glacialis at low temperatures. These species-specific effects complicate the understanding of how environmental change will influence phytoplankton populations in Arctic and sub-Arctic marine areas. In general, primary production was lower in the Bering and Chukchi Seas when compared to previous studies, however it is unknown whether differences are due to interannual variability or a trend of decreasing production. Data from both the field and laboratory component indicate a high amount of biological silicon cycling in polar environments. This study represents the first time net silicon incorporation has been measured as far north as the Chukchi Sea.

This thesis explores indicator tools to measure the ecological impacts of changes to the food system. The concept of a ‘foodshed’ provides a framework to explore the relationships between ecological impacts and where food system activities occur. Indicators of resource use and reuse are developed to describe the shape and size of the foodshed. Paper 1 presents a review of six indicator-based tools from the literature. Using a three criteria definition of ecological sustainability in the food system - increased resource efficiency, decreased pollutant loading, and increased output reuse - Paper 1 examines the suitability of these tools for evaluating the impacts of municipal food policy driven-changes in the location of activities, processes within activities and diet composition. Paper 2 describes the shape of a foodshed, and investigates how changes in Toronto’s waste management impacted the reuse of food-related nitrogen. Reuse increased from 1% in 1990 to at least 4.7% in 2001, through backyard composting and the land application of processed sewage. By 2004, in spite of household organics collection, reuse decreased to 2.3%, due to a reduction in land-applied sewage. The analysis suggests that sewage management has a larger impact on the reuse of food nitrogen than household solid waste management. Paper 3 quantifies the size of the foodsheds of Canada and the Greater Toronto Area (GTA), and evaluates the feasibility of self-sufficiency and its impact on the total land area used for production. Nationally, there is sufficient harvested land area to meet 95% of the land area needed for self-sufficiency. Self-sufficiency is only feasible for the GTA by drawing from a foodshed extending 400 kilometres beyond its boundary. Given current yields, total self-sufficiency would occupy more land area than currently used domestically and abroad. Higher yields or a change in diet could decrease the size of the foodshed.

This thesis explores indicator tools to measure the ecological impacts of changes to the food system. The concept of a ‘foodshed’ provides a framework to explore the relationships between ecological impacts and where food system activities occur. Indicators of resource use and reuse are developed to describe the shape and size of the foodshed. Paper 1 presents a review of six indicator-based tools from the literature. Using a three criteria definition of ecological sustainability in the food system - increased resource efficiency, decreased pollutant loading, and increased output reuse - Paper 1 examines the suitability of these tools for evaluating the impacts of municipal food policy driven-changes in the location of activities, processes within activities and diet composition. Paper 2 describes the shape of a foodshed, and investigates how changes in Toronto’s waste management impacted the reuse of food-related nitrogen. Reuse increased from 1% in 1990 to at least 4.7% in 2001, through backyard composting and the land application of processed sewage. By 2004, in spite of household organics collection, reuse decreased to 2.3%, due to a reduction in land-applied sewage. The analysis suggests that sewage management has a larger impact on the reuse of food nitrogen than household solid waste management. Paper 3 quantifies the size of the foodsheds of Canada and the Greater Toronto Area (GTA), and evaluates the feasibility of self-sufficiency and its impact on the total land area used for production. Nationally, there is sufficient harvested land area to meet 95% of the land area needed for self-sufficiency. Self-sufficiency is only feasible for the GTA by drawing from a foodshed extending 400 kilometres beyond its boundary. Given current yields, total self-sufficiency would occupy more land area than currently used domestically and abroad. Higher yields or a change in diet could decrease the size of the foodshed.